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Revision as of 20:09, 23 July 2005

Contents

Postfix How To: Standalone mail server with webmail only.

by CacTus


What is postfix?

Well, I think the postfix website gives a good enough definition for our purposes.

\"Postfix attempts to be fast, easy to administer, and secure, while at the same time being sendmail
compatible enough to not upset existing users. Thus, the outside has a sendmail-ish flavor, but the
inside is completely different.\"
-- http://www.postfix.org/

Goals

The goal of this how to is to setup postfix for virtual mailbox delivery only. There will be no delivery to user accounts on the box (/etc/passwd). Further, access will only be available via a web mail frontend (squirrelmail), no direct pop3 or imap access will be granted. It should be fairly easy to allow those additional features given the information below, but it is not within the scope of this document.

Required packages:

  • postfix (compiled for mysql support)
  • courier-imap
  • squirrelmail
  • mysql
  • apache
  • ssl

If you have trouble finding a package specific to this How-To, try the resources link at the bottom.

Postfix Installation

Step 1: Install Postfix

<verbatim> root@computer$ pacman -Sy postfix </verbatim>

Step 2: Check /etc/passwd, /etc/group

Make sure that the following shows up in /etc/passwd <verbatim> postfix:x:73:73::/var/spool/postfix:/bin/false </verbatim>

Make sure that the following shows up in /etc/group <verbatim> postdrop:x:75: postfix:x:73: </verbatim>

Note: Postfix can be made to run in a chroot. This document does not currently cover this. Might be added later.

Postfix Configuration

Step 1: Ensure DNS setup

For mail delivery on the internet, your dns must be correct. An MX record should point to the mail host. It should be noted that some mail servers will not deliver mail to you if your MX record points to a CNAME. For best results, always point an MX record to an A record definition.%%% More info about DNS and records, is beyond the scope of this document.

Step 2: /etc/postfix/master.cf

I don't pretend to fully understand this file yet. More info on this to come. I am studying. wink

Step 3: /etc/postfix/main.cf

Step 3.1 myhostname

set myhostname if your mail server has multiple domains, and you do not want the primary domain to be the mail host. The default is to use the result of a gethostname() call if nothing is specified.%%% For our purposes we will just set it as follows: <verbatim> myhostname = mail.nospam.net </verbatim> This is assuming that a DNS A record, and an MX record both point to mail.nospam.net%%%

Step 3.2 mydomain

this is usually the value of myhostname, minus the first part. If your domain is wonky, then just set it manually. <verbatim> mydomain = nospam.net </verbatim>

Step 3.3 myorigin

this is where the email will be seen as being sent from. I usually set this to the value of mydomain. For simple servers, this works fine. This is for mail originating from a local account. Since we are not doing local delivery (except sending), then this is not really as important as it normally would be. <verbatim> myorigin = $mydomain </verbatim>

Step 3.4 mydestination

This is the lookup for local users. Since we are not going to deliver internet mail for any local users, set this to localhost only. <verbatim> mydestination = localhost </verbatim>

Step 3.5 mynetworks and mynetwork_style

Both of these control relaying, and whom is allowed to. We do not want any relaying.%%% For our sakes, we will simply set mynetwork_style to host, as we are trying to make a standalone postfix host, that people with use webmail on. No relaying, no other MTA's. Just webmail. <verbatim> mynetwork_style = host </verbatim>

Step 3.6 relaydomains

This controls the destinations that postfix will relay TO. The default value is $mydestination. This should be fine for now. <verbatim> relaydomains = $mydestination </verbatim>

Step 3.7 home_mailbox

This setting controls how mail is stored for the users.%%% Set this to \"Maildir/\", as courier IMAP requires Maildir style mail storage. This is a good thing. Maildir format mailboxes remove the possible race conditions that can occur with old style mbox formats. No more need to deal with file locking. The '/' at the end is REQUIRED. <verbatim> home_mailbox = Maildir/ </verbatim>

Step 3.8 virtual_mail

Virtual mail is mail that does not map to a user account (/etc/passwd). This is where all the email for the system will be kept. We are not doing local delivery, remember, so if you wan't a user that has the same name as a local user, just make a virtual account with the same name.%%% First thing we need to do is add the following: <verbatim> virtualmailboxdomains = virtualdomain.tld virtualaliasmaps = hash:/etc/postfix/virtualalias, mysql:/etc/postfix/mysqlvirtual_forwards.cf virtualmailboxdomains = mysql:/etc/postfix/mysqlvirtualdomains.cf virtualmailboxmaps = mysql:/etc/postfix/mysqlvirtualmailboxes.cf virtualmailboxbase = /home/vmailer virtualuidmaps = static:5003 virtualgidmaps = static:5003 virtualminimumuid = 5003 virtualmailboxlimit = 51200000 </verbatim>

virtualmailboxdomains is a list of the domains that you want to receive mail for. This CANNOT be the same thing that is listed in mydestination. That is why we left mydestination to be localhost only.%%% virtualmailboxmaps will contain the info about the virtual users and their mailbox locations. We are using a hash file to store the more permanent maps, and these will override the forwards in the mysql database.%%%

virtualmailboxbase is the base dir where the virtual mailboxes will be stored.%%% The gid and uid maps are the real system user account that the virtual mail will be owned by. This is for storage purposes. Since we will be using a web interface, and don't want people accessing this by any other means, we will be creating this account later with no login access.%%% Virtualmailboxlimit controls the size of the mailbox. I don't know how well this works yet. I have set the size above to about 50MB.

Step 4. /etc/postfix/aliases

We need to map some aliases to real accounts. The default setup by arch looks pretty good here. =D Uncomment the following line, and change it to a real account. I put the user account on the box that I use. Best not to just send mail to root, because you don't want to be logging in as root or checking email as root. Not good. Sudo is your friend, and so is forwarding root mail. Since this is for local delivery only (syslogs and stuff), it is still within the realm of mydestination. <verbatim> root: cactus </verbatim> Once you have finished editing /etc/postfix/aliases you must run the postalias command. <verbatim> postalias /etc/postfix/aliases </verbatim>

Step 5. /etc/postfix/virtual_alias

Create /etc/postfix/virtual_alias with the following contents <verbatim> MAILER-DAEMON: postmaster postmaster: root

  1. General redirections for pseudo accounts

bin: root daemon: root named: root nobody: root uucp: root www: root ftp-bugs: root postfix: root

  1. Put your local aliases here.
  1. Well-known aliases

manager: root dumper: root operator: root abuse: postmaster

  1. trap decode to catch security attacks

decode: root

  1. Person who should get root's mail. Don't receive mail as root!

root: cactus@virtualdomain.tld </verbatim>

Then run the postalias command on it. <verbatim> postalias /etc/postfix/virtual_alias </verbatim>

Step 6. mysqlvirtualdomains.cf

Create the /etc/postfix/mysqlvirtualdomains.cf file with the following (or similar) contents: <verbatim> user = postfixuser password = XXXXXXXXXX hosts = localhost dbname = postfix table = domains select_field = 'virtual' where_field = domain </verbatim>

Step 7. mysqlvirtualmailboxes.cf

Create the /etc/postfix/mysqlvirtualmailboxes.cf file with the following (or similar) contents: <verbatim> user = postfixuser password = XXXXXXXXXX hosts = localhost dbname = postfix table = users select_field = concat(domain,'/',email,'/') where_field = email </verbatim>

Step 8. mysqlvirtualforwards.cf

Create the /etc/postfix/mysqlvirtualforwards.cf file with the following (or similar) contents: <verbatim> user = postfixuser password = XXXXXXXXXX hosts = localhost dbname = postfix table = forwardings select_field = destination where_field = source </verbatim>

Step 9. postfix check

Run the postfix check command. It should output anything that you might have done wrong in a config file. To see all of your configs, type postconf. To see how you differ from the defaults, try postconf -n

Step 10. /etc/rc.conf

Add postfix to the list of daemons. Put it near the right side, after iptables and network.%%% Put it after mysqld, as we are going to be using mysql for some of the virtual domain information storage. It is also best to put it before httpd, as it might be possible, however unlikely, for a webmail user to try something before postfix has fully started. <verbatim> DAEMONS=(syslog-ng hotplug !pcmcia iptables network netfs crond sshd mysqld postfix httpd) </verbatim>

Step 11. newuser

We need to create the user for storing the virtual mail. Create a vmialuser as follows: <verbatim> groupadd -g 5003 vmail useradd -g vmail -u 5003 -d /home/vmailer -s /bin/false vmailer mkdir /home/vmailer chown vmailuser.vmail /home/vmailer chmod -R 750 /home/vmailer passwd vmailer </verbatim> note that 5003 is the gid specified in the postfix main.cf file.%%% note that 5003 is the uid specified in the postfix main.cf file.

Mysql configuration

Step 1. Create a mysql table

Create mysql table called \"postfix\", or something similar.

Step 2. Create a mysql user

Add a user for postfix to use. Something like \"postfixuser\".%%% Give permissions for postfix user to the table. This user should be listed in the /etc/postfix/mysqlvirtualdomains.cf file.

Step 3. Setup table structure.

Import the following table structure. <verbatim> CREATE TABLE `domains` (

 `domain` varchar(50) NOT NULL default ,
 PRIMARY KEY  (`domain`),
 UNIQUE KEY `domain` (`domain`)

) ENGINEMyISAM DEFAULT CHARSETlatin1;


CREATE TABLE `forwardings` (

 `source` varchar(80) NOT NULL default ,
 `destination` text NOT NULL,
 PRIMARY KEY  (`source`)

) ENGINEMyISAM DEFAULT CHARSETlatin1;

CREATE TABLE `users` (

 `email` varchar(80) NOT NULL default ,
 `password` varchar(20) NOT NULL default ,
 `quota` varchar(20) NOT NULL default '20971520',
 `domain` varchar(255) NOT NULL default ,
 UNIQUE KEY `email` (`email`)

) ENGINEMyISAM DEFAULT CHARSETlatin1; </verbatim>

Step 4. Add a domain.

<verbatim> INSERT INTO `domains` VALUES ('virtualdomain.tld'); </verbatim>

Step 5. Add a user.

<verbatim> INSERT INTO `users` VALUES ('cactus@virtualdomain.tld', 'secret', '20971520', 'virtualdomain.tld'); </verbatim>

The above creates the user and sets a password as secret. Unfortunately, I have unable to get imap to use a hashed or crypted password here.


Test Postfix

Step 1: Start postfix

<verbatim> /etc/rc.d/postfix start </verbatim>

Step 1: Test postfix

Lets see if postfix is going to deliver mail for our test user. <verbatim> telnet servername 25 ehlo testmail.org mail from:<test@testmail.org> rcpt to:<cactus@virtualdomain.tld> data This is a test email. . quit </verbatim>

now type the following: <verbatim> find /home/vmailuser </verbatim>

you should see something like the following: <verbatim> /home/vmailuser/virtualdomain.tld/cactus@virtualdomain.tld /home/vmailuser/virtualdomain.tld/cactus@virtualdomain.tld/tmp /home/vmailuser/virtualdomain.tld/cactus@virtualdomain.tld/cur /home/vmailuser/virtualdomain.tld/cactus@virtualdomain.tld/new /home/vmailuser/virtualdomain.tld/cactus@virtualdomain.tld/new/1102974226.2704_0.bonk.testmail.org </verbatim> The key is the last entry. This is an actual email. If you see that, it is working.


Courier IMAP Installation

Step 1: Install Courier IMAP

<verbatim> pacman -Sy courier-imap courier-imap-mysql </verbatim>

Configure Courier IMAP

Step 1: /etc/courier-imap/imapd

<verbatim> ADDRESS=127.0.0.1 </verbatim>

We set the listen address to LOCAL ONLY. No outside connections.

Step 2: /etc/courier-imap/authdaemonrc

<verbatim> authmodulelist=\"authmysql\" </verbatim>

Step 3: /etc/courier-imap/authmysqlrc

<verbatim> MYSQL_SERVER localhost MYSQL_USERNAME dbuser MYSQL_PASSWORD secretpass! MYSQL_SOCKET /tmp/mysql.sock MYSQL_DATABASE dbname MYSQLUSERTABLE users MYSQLCLEARPWFIELD password MYSQLUIDFIELD '5003'

    1. note, this is the uid that we set in /etc/postfix/main.cf

MYSQLGIDFIELD '5003'

    1. note, this is the gid that we set in /etc/postfix/main.cf

MYSQLLOGINFIELD email MYSQLHOMEFIELD \"/home/vmailer\" MYSQLMAILDIRFIELD concat(domain,'/',email,'/') MYSQLQUOTAFIELD quota </verbatim>


Step 6: /etc/conf.d/courier-imap

First start the courier-imap daemon then stop it right away. I don't know exactly what this does (if anything.lol), but I have attempted the following step without having fulfilled that precondition and it borked on me. shrug %%% A quick <verbatim> /etc/rc.d/courier-imap start /etc/rc.d/courier-imap stop </verbatim> should be enough. %%% Now, remove the pop3d listings from courier-imap. We are only using the imap facility. Since the daemon is local only (localhost), we do not need the ssl imapd server either. %%% /etc/conf.d/courier-imap <verbatim> CI_DAEMONS=\"imapd\"

  1. CI_DAEMONS=\"imapd pop3d imapd-ssl pop3d-ssl\"

</verbatim>

Step 7: Add courier-imap to rc.conf

<verbatim> DAEMONS=(syslog-ng hotplug !pcmcia iptables network netfs crond sshd mysqld postfix courier-imap httpd) </verbatim>

Again, make sure to add courier after postfix, after mysqld and after postfix, yet before httpd.

Step 8: Fam and portmap

Courier-imap for arch comes compiled with FAM. This means portmap is also required.%%% If portmap is not already installed: <verbatim> pacman -Sy portmap </verbatim>

Then add the following to /etc/hosts.allow <verbatim> portmap:localhost 127.0. </verbatim>

Now edit /etc/fam/fam.conf <verbatim> local_only = true idle_timeout = 0 </verbatim> Make sure the two above values are set.

Now add portmap and fam to the daemons list in /etc/rc.conf <verbatim> DAEMONS=(syslog-ng hotplug !pcmcia iptables network netfs crond sshd mysqld postfix portmap fam courier-imap httpd) </verbatim> Make sure that portmap starts after network, but before fam, and fam starts before courier.%%% Now start them. <verbatim> /etc/rc.d/portmap start /etc/rc.d/fam start </verbatim>

Step 9: Start courier imap

<verbatim> /etc/rc.d/courier-imap start </verbatim>

check /var/log/mail.log for any errors.

Step 10: Test courier..

Lets see if courier is working: <verbatim> telnet localhost imap Trying 127.0.0.1... Connected to localhost.localdomain. Escape character is '^]'.

A LOGIN \"cactus@virtualdomain.tld\" \"password\" A OK LOGIN Ok.

B SELECT \"Inbox\"

B OK READ-WRITE Ok

Z LOGOUT

  • BYE Courier-IMAP server shutting down

Z OK LOGOUT completed Connection closed by foreign host. </verbatim>


Squirrelmail Installation

Step 1: Install Squirrelmail

You can either download it from the squirrelmail website, or you can use the one packaged in the repos. <verbatim> pacman -Sy squirrelmail </verbatim>

Configure Squirrelmail

Step 1: Create secure http site (https)

We are going to create a secure http site. This is so that people can login with plain text passwords, and not have to worry about the passwords getting sniffed (or worry less).

Step 1.1: Edit /etc/httpd/conf/ssl.conf

Add appropriate information. Here is an example section:

<VirtualHost ''default'':443>
#  General setup for the virtual host
DocumentRoot \"/home/httpd/site.virtual/virtualdomain.tld/html\"
ServerName virtualdomain.tld:443
ServerAdmin noemailonthisbox@localhost
<Directory \"/home/httpd/site.virtual/virtualdomain.tld/html\">
    Options -Indexes +FollowSymLinks
    AllowOverride Options Indexes AuthConfig
    Order allow,deny
    Allow from all
</Directory>

Step 1.2: Create the directory structure

Now, create the directory you specified in the ssl.conf file. <verbatim> mkdir -p /home/httpd/site.virtual/virtualdomain.tld/html </verbatim>

Step 1.3: Generate a certificate

Follow the instructions in the /etc/httpd/conf/mod_ssl.txt file.

Step 1.4: Restart apache and test

Make sure that https is now working, and that you can get to the secure site.

Step 2: Put squirrelmail in the directory you created

Either extract squirrelmail, or move it from where the arch package puts it, into the directory you created for the secure http site.

Step 3: Run squirrelmail config utility

cd 'squirrelmaildir'/config <verbatim> perl conf.pl </verbatim>

Make sure you select 'D', then type in courier and hit enter. Make sure your other options are correct as well.%%% Note: If you use php with safe mode on, make sure that the data dir is owned by the same owner as all the files in the squirrelmail directory. With safe mode off, simply follow the squirrelmail setup directions.

Step 4: Test the squirrelmail setup

Log in with the test account. You will need to login with the form of: %%% username: cactus@virtualdomain.tld %%% password: secret

Try sending email to non-existent local accounts. You should get an immediate bounce back. %%% Try sending email to external good email accounts, as well as non-existent ones. %%% Just general testing stuff.%%% If everything works fine, then you can add other accounts to the mysql database, and away you go!

Resources:

You can find postfix compiled with mysql support located [[|http://cactuswax.net/~eliott/archlinux/binary-packages/ Here]]


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